Symbol TryAddValue(Type ty, int op, Symbol src1, Symbol src2)
{
int h = ((unsigned)src1 + (unsigned)src2 + op) & 15;
ValueDef def = FSYM->valNumTable[h];
Symbol t;
if (op != ADDR && (src1->addressed || (src2 && src2->addressed)))
goto new_temp;
while (def)
{
if (def->op == op && (def->src1 == src1 && def->src2 == src2))
break;
def = def->link;
}
if (def && def->ownBB == CurrentBB && def->dst != NULL)
return def->dst;
new_temp:
t = CreateTemp(ty);
GenerateAssign(ty, t, op, src1, src2);
def = AsVar(t)->def;
def->link = FSYM->valNumTable[h];
FSYM->valNumTable[h] = def;
return t;
}
/* 折半查找 */
static void TranslateSwitchBuckets (SwitchBucket *bucketArray, int left, int right, Symbol choice, BBlock currBB, BBlock defBB)
{
int mid, len, i;
AstCaseStatement p;
BBlock lhalfBB, rhalfBB;
BBlock *dstBBs;
Symbol index;
if (left > right)
return;
mid = (left + right) / 2;
lhalfBB = (left > mid - 1) ? defBB : CreateBBlock();
rhalfBB = (mid + 1 > right) ? defBB : CreateBBlock();
len = bucketArray[mid]->maxVal - bucketArray[mid]->minVal + 1;
dstBBs = HeapAllocate (CurrentHeap, (len + 1)* sizeof(BBlock));
for (i = 0; i < len; ++i)
dstBBs[i] = defBB;
dstBBs[len] = NULL;
for (p = bucketArray[mid]->cases; p; p = p->nextCase) {
i = p->expr->val.i[0] - bucketArray[mid]->minVal;
dstBBs[i] = p->respBB;
}
if (currBB != NULL) {
StartBBlock (currBB);
}
GenerateBranch (choice->ty, lhalfBB, JL, choice, IntConstant (bucketArray[mid]->minVal));
StartBBlock (CreateBBlock());
GenerateBranch (choice->ty, rhalfBB, JG, choice, IntConstant (bucketArray[mid]->maxVal));
StartBBlock (CreateBBlock());
if (len != 1) {
index = CreateTemp (choice->ty);
GenerateAssign (choice->ty, index, SUB, choice, IntConstant (bucketArray[mid]->minVal));
GenerateIndirectJump (dstBBs, len, index);
} else {
GenerateJump (dstBBs[0]);
}
StartBBlock (CreateBBlock ());
/* 二分递归 */
TranslateSwitchBuckets (bucketArray, left, mid - 1, choice, lhalfBB, defBB);
TranslateSwitchBuckets (bucketArray, mid + 1, right, choice, rhalfBB, defBB);
}
Symbol Deref(Type ty, Symbol addr)
{
Symbol tmp;
if (addr->kind == SK_Temp && AsVar(addr)->def->op == ADDR)
{
return AsVar(addr)->def->src1;
}
tmp = CreateTemp(ty);
GenerateAssign(ty, tmp, DEREF, addr, NULL);
return tmp;
}
/* 尝试添加操作的值
* 在函数符号表中查找该操作,
* 如果找到复合条件的则返回目标符号,
* 否则创建值并添加到符号表中 */
Symbol TryAddValue (Type ty, int op, Symbol src1, Symbol src2)
{
int h = ((unsigned long long)src1 + (unsigned long long)src2 + op) & 15;
ValueDef def;
Symbol t;
/* 非地址符号 */
if (op != ADDR && (src1->addressed || (src2 && src2->addressed)))
goto new_temp;
/* 在函数的符号表中查找此操作的值 */
for (def = FSYM->valNumTable[h]; def; def = def->link) {
if (def->op == op && (def->src1 == src1 && def->src2 == src2))
break;
}
/* 如果查找到该值,并属于当前基本块,并且有目标符号,则直接返回,
* 否则创建中间变量 */
if (def && def->ownBB == CurrentBB && def->dst != NULL)
return def->dst;
/* 创建新临时变量 */
new_temp:
/* 创建临时变量添加到函数符号表中 */
t = CreateTemp (ty);
/* 构造一个三地址码,并添加到当前块中 */
GenerateAssign (ty, t, op, src1, src2);
/* t->def 是在GenerateAssign 中构造的值 */
def = AsVar(t)->def;
/* 添加值到符号表中 */
def->link = FSYM->valNumTable[h];
FSYM->valNumTable[h] = def;
return t;
}
